The present invention relates to an electro-luminescence (EL) lamp, and more particularly to a dispersion type EL lamp emitting light in multiple colors.
An example of dichroic emission-dispersion type EL lamp is described by reference to FIG. 5 to FIG. 7 as a conventional multi-color emission-dispersion type EL lamp.
For the ease of understanding of constitution, the drawings are shown in magnified dimensions in the thickness direction.
FIG. 5 is an outline perspective view of a conventional dichroic emission-dispersion type EL lamp. FIG. 6 is a sectional view inverted in vertical and lateral direction along line 71-72 in FIG. 5. FIG. 7 is a sectional view inverted in vertical and lateral direction along line 81-82 in FIG. 5.
In FIG. 5, FIG. 6 and FIG. 7, the conventional dichroic emission-dispersion type EL lamp comprises a luminous plane 1 of the EL lamp, a plurality of external lead-out electrodes 2, 3 of light-permeable electrode layers composed inside, and an external lead-out electrode 4 of back electrode layer, and these external lead-out electrodes 2, 3 and external lead-out electrode 4 are provided at the side of the luminous plane 1.
In the magnified sectional views of FIG. 6 and FIG. 7, the conventional EL lamp comprises a transparent resin film 5 having a luminous plane 1, a first light-permeable electrode layer 6 printed and formed on other side of the transparent resin film 5, a first luminous material layer 7 printed and formed on the first light-permeable electrode layer 6, a second light-permeable electrode layer 8 printed and formed n the first luminous material layer 7, a luminous color converting layer 9 printed and formed on the second light-permeable electrode layer 8, a third light-permeable electrode layer 10 printed and formed on the luminous color converting layer 9, a second luminous material layer 11 printed and formed on the third light-permeable electrode layer 10, a back electrode 12 printed and formed on the second luminous material layer 11, and an insulating protective layer 13 for covering all layers.
The external lead-out electrodes 2, 3 are connected to the first light-permeable electrode layer 6, second light-permeable electrode layer 8 and third light-permeable electrode layer 10. The external lead-out electrode 4 is connected to the back electrode layer 12. The opposite side of the transparent resin film 5 forming the layers is the luminous plane 1.
The first light-permeable electrode layer 6 contains a transparent resin and a tin indium oxide powder dispersed in this transparent resin. The first luminous material layer 7 contains a highly dielectric resin such as cyano resin or fluororubber resin, and a granular fluorescent material dispersed in this highly dielectric resin. The fluorescent material has copper-doped zinc sulfide or the like. The second light-permeable electrode layer 8 contains a transparent resin and a tin indium oxide powder dispersed in this transparent resin. The luminous color converting layer 9 contains a transparent resin and a fluorescent pigment or fluorescent dye dispersed in this transparent resin. The fluorescent pigment or fluorescent dye has a luminous color of a longer wavelength than the luminous color of the first luminous material layer. The third light-permeable electrode layer 10 contains a transparent resin and a tin indium oxide powder dispersed in this transparent resin. The second luminous material layer 11 contains a highly dielectric resin and a granular fluorescent material dispersed in this highly dielectric resin. The fluorescent material has copper-doped zinc sulfide or the like. The insulating protective layer 12 contains a silver resin system paste or carbon resin system paste.
The thickness of the constituent layers in FIG. 5, FIG. 6 and FIG. 7 are magnified in view, and the actual thickness of each layer is about 1 xcexcm to about 90 xcexcm, except for the transparent resin film.
In such dichroic emission-dispersion type EL lamp, the fluorescent material for obtaining a practical emitting luminance and luminance life has cool colors such as blue and green. Therefore, the first luminous material layer 7 has a cool luminous color having a fluorescent material of blue or green luminous color dispersed in a synthetic resin. The second luminous material layer 11 also has cool luminous colors such as blue and green. The luminous color converting layer 9 has warm colors such as orange, red, pink and yellow of longer wavelength than cool luminous colors. The luminous color converting layer 9 has a function of converting the cool luminous color emitted from the second luminous material into a warm luminous color. In such constitution, when light is emitted from the first luminous material layer 7, the cool luminous color is released from the luminous plane. When the second luminous material layer 11 is illuminated, the luminous color converted into a warm color tone is released from the luminous plane. Thus, different luminous colors are obtained. To illuminate the first luminous material layer 7, a specified voltage is applied between the external lead-out electrode 2 and external lead-out electrode 3. To illuminate the second luminous material layer 11, a specified voltage is applied between the external lead-out electrode 3 and external lead-out electrode 4.
Each one of the first luminous material layer 7 and second luminous material layer 11 has two-layers in order to enhance the emitting luminance. A first layer of the two layers contains a transparent highly dielectric resin, and a fluorescent powder dispersed in the resin, and a second layer has a highly dielectric resin, and a highly dielectric fine powder such as barium titanate dispersed in the resin.
In such conventional multi-color emission-dispersion type EL lamp, however, when the first luminous material layer 7 is illuminated, the light emitted from the first luminous material layer 7 is reflected by the luminous color converting layer 9 disposed at the back side of the first luminous material layer 7, and this reflected light is released to the face side. Accordingly, the luminous color released to the face side of the first luminous material layer 7 is interfered by the reflected light. As a result, the original color of the first luminous material layer 7 is hardly released from the luminous plane.
For example, in the constitution in which the first luminous material layer 7 has a fluorescent material of blue luminous color, and the luminous color converting layer 9 has a fluorescent pigment of red luminous color, when the first luminous material layer 7 is illuminated, the blue luminous color released from the luminous plane 1 is interfered by the red reflected light of the luminous color converting layer 9, and a nearly white color is released from the luminous plane. It was thus difficult to obtain the original blue luminous color.
In particular, when such conventional multi-color emission-dispersion type EL lamp is used as the backlight of a translucent type liquid crystal display device, the translucent film of the translucent type liquid crystal display device reflects about 70% to about 90% of the light released from the multi-color emission-dispersion type EL lamp. Therefore, the reflected light is reflected to the luminous color converting layer in the multi-color emission-dispersion type EL lamp, and its reflected light is released to the liquid crystal display device side. Such reflection is repeated. As a result, the color interference is further promoted, and the problem becomes more manifest.
It is hence an object of the invention to present a multi-color emission-dispersion type EL lamp capable of suppressing color interference by reflected light due to other colored constituent materials, and obtaining a plurality of clear luminous colors from the luminous plane side.
The invention provides an EL lamp for emitting light in multiple colors from the front surface side of a transparent substrate, which comprises:
(a) the transparent substrate,
(b) a first light-permeable electrode layer formed at the back side of the transparent substrate,
(c) a first luminous material layer having a first luminous material, disposed at the back side of the first light-permeable electrode layer,
(d) an intermediate light-permeable electrode layer disposed at the back side of the first luminous material layer,
(e) a second luminous material layer having a second luminous material, disposed at the back side of the second light-permeable electrode layer,
(f) a back electrode layer disposed at the back side of the second luminous material layer, and
(g) at least two elements selected from the group consisting of:
(i) a first color material contained in the first luminous material layer,
(ii) a second color material contained in the second luminous material layer,
(iii) a luminous color converting layer containing a third color material, disposed between the first luminous material layer and second luminous material layer, and
(iv) a color coat layer containing a fourth color material, disposed at the front surface side of the transparent substrate,
in which the color material closer to the back electrode of the at least two elements has a color of longer wavelength than the remoter color material.
Preferably, the color of longer wavelength has a color of longer wavelength than the first luminous color emitted by the first luminous material.
Preferably, the first luminous material and second luminous material emit a same luminous color.
Preferably, the color of longer wavelength has a color of longer wavelength than the first luminous color emitted by the first luminous material, the first luminous material and second luminous material emit a same luminous color, the color of longer wavelength has a color of longer wavelength than the same luminous color.
Preferably, each color material of the first color material, second color material, third color material, and fourth color material contains at least one of fluorescent pigment and fluorescent dye.
Preferably, the transparent substrate is a transparent resin film, the first luminous material layer has a first transparent resin, the first luminous material layer is dispersed in the first transparent resin, the second luminous material layer has a second transparent resin, and the second luminous material layer is dispersed in the second transparent resin.
In this constitution, when a first color light having a first color is emitted from the first luminous material layer, a clear first color light is released from the luminous plane side without having effects of color materials contained in other layers. Further, when a second color light having a second color is emitted from the second luminous material layer, a clear third color light converted in color is released from the luminous plane side without having effects of color materials contained in other layers. As a result, a plurality of clear luminous colors are released from the luminous plane.